1. Technical Field
The invention relates to agricultural tractors and in particular to the front end installations of such which includes an engine and a cooling package supported in front of a cab.
2. Description of Related Art
The basic layout of agricultural tractors has not changed for several decades and typically includes a cab supported upon a transaxle which includes a rear axle and a transmission casing as an integrated part. Typically, the engine casing is attached to the front of the transmission via a clutch housing wherein the primary drive shaft runs from the engine to the transmission along a generally central and longitudinal axis.
Other components associated with the engine are housed under a hood together in front of the drivers cab. The most significant of these components is the cooling package which typically includes one or more radiators (or coolers) and a fan for propelling a cooling air stream through the radiators. As with many self-propelled vehicles, the cooling package of known agricultural tractors is disposed forwardly of the engine to have access to an uninterrupted source of clean air through a grill in the front of the hood.
DE-203,10,200-U1 discloses a cooling system having three radiators in a U-configuration with one standing vertically and located at the front of the vehicle and two on respective sides and aligning with a longitudinal axis.
As agricultural machinery increases in size (to benefit from economies of scale), so too does the size of wheeled agricultural tractors required to power that machinery. Currently available models are approaching 400 hp in size. Larger engines demand larger cooling packages and various attempts have been made to accommodate the larger components under the hood whilst minimizing any obstruction to the driver's forward field of vision.
In some countries, safety legislation limits the maximum distance at which the driver's forward field of view begins. Limits on the forward view are determined by the height of the driver's position and the geometry of the hood. These restrictions on the size of the hood limit the size of the cooling package which, in turn, limits the engine size.
Attempts to incorporate larger cooling packages have involved tilting radiators for example. However this has been found to come at the expense of reduced cooling capacity and restricted air flow.
Another drawback of wider front end installations is the reduction in steering capability of the tractor. Wider installations demand a wider supporting frame which in turn limits the angle at which steerable wheels on the front axle can reach.
Yet another drawback of wider front end installations is the restriction placed on the driver's view of a front linkage assembly. Although not fitted to all agricultural tractors, front linkages should be visible to a driver to allow an efficient and safe coupling process. Without a good view of the front linkage lower links a driver is required to repeatedly dismount from the tractor to check the relative tractor/implement position or employ a second person to aid with the attachment.